The application claims the benefit of 60/994,547 filed Sep. 19, 2007.
High definition televisions (HDTVs) include image up-conversion techniques to properly display standard definition video content on the high definition television at a high definition resolution. Traditional spatial up-conversion techniques include linear interpolation such as bilinear/bi-cubic interpolation. Unfortunately, the linear techniques increases the number of pixels, but not the high frequency part of the spectrum, and therefore does not increase the perceived sharpness of the image.
To increase the perceived sharpness in the up-converted image, training-based content-adaptive techniques have been used. This type of training-based content-adaptive interpolation techniques has two phases: the training phase and the interpolation phase. The training phase is done offline by using a number of low-resolution (LR) images and their high-resolution (HR) counterparts as training data to define relationships between the LR images and the HR images. In the training phase, different sets of linear filter coefficients are derived from the training data for different local contents. The interpolation phase is done on-line by interpolating LR images not in the training data. In the interpolation phase, a set of the linear filter coefficients for a particular position in the LR image is chosen to interpolate HR pixels around that positions based on the local content. Although locally the interpolation is based on linear filtering, but because of the content adaptation of the linear filter coefficients, globally this type of the technique is non-linear.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.